Implementation of the i18n:choose directive which provides plural
internationalisation of strings.

This directive requires at least one parameter, the one which evaluates to
an integer which will allow to choose the plural/singular form. If you also
have expressions inside the singular and plural version of the string you
also need to pass a name for those parameters. Consider the following
examples:

Note that elements defining xml:lang attributes that do not contain
variable expressions are ignored by this filter. That can be used to
exclude specific parts of a template from being extracted and translated.